CORRECTS SPELLING TO LEE MYUNG -BAK INSTEAD OF LEE MUNG-BAK- South Korean President Lee Myung-bak speaks to the nation during a press conference to mark his retirement at the presidential house in Seoul, South Korea, Tuesday, Feb. 19, 2013. During the address, Lee warned North Korea has pushed itself further into a corner with its recent nuclear test. (AP Photo/Yonhap, Do Kwang-hwan) KOREA OUT

CORRECTS SPELLING TO LEE MYUNG -BAK INSTEAD OF LEE MUNG-BAK - People watch a television airing a live broadcast of South Korean President Lee Myung-bak's retirement speech at Seoul Railway Station in Seoul, South Korea, Tuesday, Feb. 19, 2013. During his address, Lee warned North Korea has pushed itself further into a corner with its recent nuclear test. (AP Photo/Ahn Young-joon)

South Korean protesters burn an effigy of North Korean leader Kim Jong Un during an anti-North Korea rally denouncing the North's nuclear test in Seoul, South Korea, Wednesday, Feb. 13, 2013. A day after North Korea defied U.N. warnings with a nuclear test, Pyongyang’s neighbors turned Wednesday to the business of bolstering their military preparations and sending out scientists to determine whether the detonation was as successful as the North claimed. (AP Photo/Ahn Young-joon)

A man looks through the wire fence covered with ribbons carrying messages of people's wish for the reunification of the two Koreas at the Imjingak Pavilion near the border village of Panmunjom, which has separated the two Koreas since the Korean War, in Paju, north of Seoul, South Korea, Wednesday, Feb. 13, 2013. Defying U.N. warnings, North Korea on Tuesday conducted its third nuclear test in the remote, snowy northeast, taking a crucial step toward its goal of building a bomb small enough to be fitted on a missile capable of striking the United States. (AP Photo/Lee Jin-man)

South Korean army soldiers patrol by the national flags and ribbons, wishing for the reunification of the two Koreas, attached on the barbed-wire fence at the Imjingak Pavilion near the border village of Panmunjom, which has separated the two Koreas since the Korean War, in Paju, north of Seoul, South Korea, Wednesday, Feb. 13, 2013. Defying U.N. warnings, North Korea on Tuesday conducted its third nuclear test in the remote, snowy northeast, taking a crucial step toward its goal of building a bomb small enough to be fitted on a missile capable of striking the United States. (AP Photo/Lee Jin-man)

A South Korean protester shouts slogans near an effigy of North Korean leader Kim Jong Un during an anti-North Korea rally to denounce North Korea's nuclear test in Seoul, South Korea, Wednesday, Feb. 13, 2013. A day after North Korea defied U.N. warnings with a nuclear test, Pyongyang’s neighbors turned Wednesday to the business of bolstering their military preparations and sending out scientists to determine whether the detonation was as successful as the North claimed.(AP Photo/Ahn Young-joon)

South Korean army soldiers patrol along barbed-wire fences at the Imjingak Pavilion, near the demilitarized zone of Panmunjom, in Paju, South Korea, Tuesday, Feb. 12, 2013. South Korea is confirming that North Korea has tested a nuclear device in defiance of U.N. orders to stop building atomic weapons. (AP Photo/Ahn Young-joon)

On a large television screen in front of Pyongyang's railway station, a North Korean state television broadcaster announces the news that North Korea conducted a nuclear test on Tuesday, Feb. 12, 2013. North Korea conducted a nuclear test at an underground site in the remote northeast Tuesday, taking an important step toward its goal of building a bomb small enough to be fitted on a missile that could reach United States. The TV screen text reads: "Korean Central News Agency reports," and "The third underground nuclear test successfully conducted."(AP Photo/Kim Kwang Hyon)